This relates generally to imaging systems and, more particularly, to imaging systems having curved image sensors.
Modern electronic devices such as cellular telephones, cameras, and computers often use camera modules with digital image sensors. Imagers (i.e., image sensors) often include a two-dimensional array of image sensing pixels. Each pixel typically includes a photosensitive element such as a photodiode that receives incident photons (light) and converts the photons into electrical signals. Typically, image sensors are formed on a flat plane.
In one possible arrangement, a simple lens is used to focus image light onto the image sensing pixels. However, a simple lens generates a curved focal plane. This is problematic when focusing image light onto a flat image sensor, as applying the curved focal plane to a flat image sensor results in reduced image quality. To solve this problem, a multi-element lens is typically used to generate a flat focal plane. Using a multi-element lens to focus image light increases image quality for flat image sensors. However, these multi-element lenses are much more expensive than using a simple lens. Additionally, the multi-element lens results in the camera module having a greater z-height than otherwise necessary.
One way to reduce the complexity and size of lenses in a camera module is to use curved image sensors. A curved image sensor can be designed to match the curvature of a simple lens's curved focal plane. This reduces both the cost and height of the camera module. Curving an image sensor can also provide a performance advantage by decreasing the dark current generated by the image sensor. However, forming curved image sensors is difficult as the image sensors are very thin and therefore extremely fragile.
It would therefore be desirable to provide improved ways of forming curved image sensors.